Field of the Invention
This invention relates to an offshore platform for producing oil from a well drilled to an underground hydrocarbon reservoir beneath the body of the water in which the platform is located. It relates especially to a structure for protecting the wellhead and the platform from damage due to fire. The term "wellhead", as used here, includes the "Christmas tree", which, in turn, includes the master valves, tee, swab valves, and wing valves, which sit on top of the casing spool and hanging equipment. It concerns particularly the placing of the wellhead beneath the surface of the body of the water and includes means whereby the wellhead can be sealed to a cylindrical cellar which extends above the water and from which the water can be removed so that the wellhead is in an atmospheric environment.